卡口地形段泥石流堵塞效应分析——以四川什邡桦头尖泥石流沟域为例

Blocking effect of debris flow in the segment of bayonet terrain:A case study at the Huatoujian gulley of Shefang,Sichuan

泥石流在流经卡口段沟道时常出现暂时堵塞现象,并伴随着流量放大效应。文章通过典型卡口段泥石流野外调查和室内水槽试验,研究卡口段泥石流堵塞效应的影响因素与成因机制。研究显示:卡口段泥石流堵塞效应引起的流量放大或因松散固体物源堆积而产生的流量衰减,均与卡口部位的几何条件、泥石流流体、沟域特征、是否存在附加松散物源有关。单纯卡口的存在多为泥石流流量衰减的正面因素,而是否有松散物源的加入则是卡口段泥石流的堵塞效应发生的关键因素。此研究对认识泥石流在微地貌突变动、堆积规律,完善泥石流防治技术规程方面都具有重要的理论意义和应用前景。

The temporary block-breach phenomena tend to occurrence when debris flows run throng bayonet segment,accompanying with instant scale-amplified effect.By the way of field investigations as well as indoor flume tests,the influence factors and formation mechanisms of the block-breach effect were studied herein.Results showed that the flow amplification caused by the blocking effect of debris flow or the flow attenuation caused by the accumulation of solid materials in the bayonet segments,were related to the geometric conditions of the bayonet,the debris flow fluid and trench features,and whether there was additional loose material.The existence of bayonet was mostly a positive factor for the flow attenuation of debris flow,and whether there was the addition of loose materials was the key factor for the blocking effect of debris flow in bayonet segments.This study provided theoretical significance and application prospects for understanding the motional and deposited regularities of debris flow in where micro-topography abruptly changed,and improving the technical regulations of natural hazard prevention and mitigation.